An organic EL display has features that the simplification of a drive circuit can be achieved because of being driven by a direct current voltage, dependency of viewing angle like a liquid crystal display can be reduced, and a bright image can be obtained owing to self luminescence. Furthermore, because of having an advantage of fast response time or speed, the organic EL display is paid to attention as a flat display panel.
In a producing method of such kind of the organic EL display, anodes, organic films, and cathodes are firstly laminated using a vapor deposition on a transparent electrode glass as a glass substrate thereby forming organic EL elements and wiring patterns. Next, each of the organic EL elements formed on the transparent electrode glass is covered by a metal cap (protecting plate or protecting member) formed of SUS, Al and so forth, and the metal caps are fixed adhesively on the transparent electrode glass. Finally, the transparent electrode glass is divided with each organic EL element, thereby producing organic EL displays (refer to Patent Document 1).
Incidentally, in order to reduce the thickness of the organic EL display, a method of etching is adopted in which the glass substrate as a transparent substrate is etched using an etching liquid, such as a hydrofluoric acid solution.
However, there is a fear that the metal cap corrodes when the metal cap is immersed into the etching liquid. On the other hand, in case that a masking sheet is adopted to mask a main surface of the glass substrate to which the etching is unnecessary in order to protect the metal cap from corrosion due to the etching liquid, there are fears that the wiring patterns might be damaged by being contacted with the masking sheet, and static electricity charged in the masking sheet causes adverse effects on the organic EL elements.
[Patent Document 1] Japanese Patent Gazette No. 3,626,728